Lock mechanism



G. D. HILL LOCK MECHANISM Jan. 29, 19 35.

2 Sheets-Sheet 1 Filed April 21, 1931 INVENTOR @rrLZZHLZL Jgm. 29, 1935.e. D. HILL 9 LOCK/MECHANISM Filed April 21, 1931 2 Sheets-Sheet 2Patented Jan. 29, 1935 i UNITED 'STATE5PATENT Sargent 8t Greenleaf,Inc.,- Rochester, N. Y., a corporation of New York Application April 21,1931, Serial No. 531,736 16 Claims. (01. 70-26) H This invention relatesto a lock mechanism within the member 14' so that by turning the han--which may be used, for example, in connection dle 16 the member 14 andthe bolts 12 may be with a safe or vault. An object of the inventionmoved back and. forth from looking to unlocking the provision of lockmechanism of simple position, and vice versa, wheneversuchmoveoicharacter, having relatively few moving parts, ment is notobstructed by one or another. of .the;.--

employing noclockwork, springs, escapement, or look mechanisms employed.gears, which cannot be circumvented from the; At 20 there is illustratedconventionally'a casoutside of the safe or'vault. i 1 ing of acombination lock of any usual orordinary Another object of the inventionis the=provision Co st uction havin t usual Operating spindle of a lockmechanismoperative to release a bolt or 21 connected to the usual knobon the outsidexof 10 the like after a, predetermined time interve1, thedoor. A disk 22 is fixed to the spindle near the which mechanism issimple and relatively inexinner end thereof. ,When the tumblers havebeenpensive to construct, which is accurately timed, Properly set bymanipulation ofthe kn'obythe bolt and which is fully automatic so that nsprings 23 of the combination lockmay be withdrawn' so "need be woundand no settings-need be made preha i 0 l n r obstructs unlockingmovement of viously inorderto insure properoperation of the e be twork0f the door. i J timingmechanism at the desired ti e, Also mounted onthe inner face of the door 11 A further object is the provision of sucha time there is .a time: 100k c an s .O novel and lock mechanism in,combination with another greatly p fi d form, w c in t p ese p Ilock, sothat operation of'the other lock will inir d embodiment mploys 110 Sprngs, gearsi'orfi .tiate o crationofthe time lock mechanism. o k o a dwhich is p e a d c mp a v y T th andtothepd th inv ti id inexpensive toconstruct. This time, lock mechain certain improvements and combinationsof ah s Operates on t general p p pparts, all as will be hereinaftermore fully de- P a qua t ty of fluid and then releasing this ;seribed,thve1 f at r being pointed t fluid at a predetermined relativelyslow rate,vso. 2 5

the claims at the end of the specification. i that it takes apredetermined time interval for a In the drawings: 1 a r given quantityof the trapped fluid toescape. Fig; 1 isan elevation f the inside faceof a safe a After t predetermined qua y as p d, oor showingtheapplication of one embodimen d-not until then, the mechanism ismoved-to- 30. of th r ti v nti th t unlocked position so that theboltwork-or otherc3 'Fig. 2 is a fragmentaryview of some of the desiredparts controlled by the time, lock mechaparts shown in Fig. 1,illustrating them in a. difnism y be moved in the desired'way. 'ferentiti 3 The-term fluid as used here and inthe ac- Fig. 3 is a fragmentaryview of part of theapcompanyingclaims is intended in a broad 'senseparatus shown in Fig. 1 ona larger scale, with and is meant toincludenot-only substances which 13 parts in vertical section; 4 aretechnically fluids, such as liquid'and gas, but -Fig. 4 is avertical'seetion illustrating detail also solid substances of relativelysmall'size which of one embodiment of the time lock mechanism,Collectively e capable L OW' S mew at like Fig. 5 is a similar viewillustrating details of ane a y the uid'which is trap n s10W- otherembodiment of theinvention. I y r as d s s a ed 'pla y a av r fluid.

Similar reference numerals throughoutgthe h appa u t a edh y way fixseveral views i i t t Same par1;s ample has'been designed to use a gasas .the a In Fig. 1 there is shown diagrammatically a 'lightel' fiuWhich is t p and a iquid as door 11 of a safe'or vault, thedoor havingbolts 12 the avi fluid which holds-it inxp mounted thereon, connected toeach other by a viously other forms ofeapparatus may be made bar 13which in turn is connected to a horizontal falling within the spirit ofthis invention; Without bar 14. The bar 14 thus forms part oftheboltnecessarily u g a-liquid to seal a t work of the safe and, as itcontrols the movements j The present apparatus has also been designed ofthe bolts 12, the member 14 may itself be deto useordinary air as thegasiwhich istrapped, 5 scribed broadly as abolt. I and mercury as theliquid which sealsthe gas,

A handle spindle 15 passing through the safe but these featureslikewise, while they are'predoor 11 is provided with a handle 16 on theexteferred in the present instance, are not to be conriorlof the door,and with an arm 17 on the intesidered controlling and. may be discarded,withr ot. oi e d e 1 Th m i s a lot; is ;.out departing from the spiritof'theinventions)" suitable sealing liquid, such as mercury. At the topof the receptacle there is provided an aperture 28 through which a stem29 extends loosely. To the lower end oflthisstemsinside the receptacle25 there is fixed a.-chamber, 3.0 which may be described in general asinverted cup like,

or of an inverted cup shape. As will be clearly seen from the drawings,the-chamber30'has a substantially flat top through which wthe stem 29extends and to which it is secured with an air ctightconnection. .Thesidewalls of the chamber ;-are:prferably substantially cylindrical andof such size sand.- so .positioned that. they may move -=J.1pandidownifreely in the annular space 2'7 above 'ldeSCIibBd. ilThe crosssectional shape of the chamber as cut by a substantially horizontalplane may: be circular, oval; rectangular, or of any other {form.desired.

. zErom'the .parts'thus far .describedit -will*be lreadilymnderstoodthatair or any other suit- 'ablesgaszmayenterithereceptacle 25 through theraperturer28, since the stem 29 passes loosely :through .it -.:without atight fit. Whenever the rchamberJBO iszraisedato such a position thatthe l'lowerledge 31.thereof isabove the liquid level 32 of the mercuryor-other sealing "liquid =employe'd; then airror other fluid may'enterand Jflll thezint'erior of the-chamber 30. Then-if the --achamber :be"dropped slightly downwardly until "Iheilower edge 31 thereof 1 isslightly immersed tin :the :sealing "liquid, the fluid trapped in themhamber will be sealed --therein and -cannot"es ,:-'slightldownwardmovement of "the-chamber '30 amayrtakeplace until the trapped fluid is--com- :pressed :to'i'an extent suflicient to equalize -the .zpressurecaused I-by ;.the weight of the chamber :30 and parts .ssupportedthereby, but when the seqmlibriumis reached it is obvious thatnofur-.ther downward -movement-of the chamber-can take :place i unless and 1until some i of the trapped sage relatively slowly The porous materialmay fluid is released from the chamber.

Accordingtd-thepresent invention the trapped fluid is relea'sed at r apredetermined rate, so that after the above mentioned point ofequilibrium hasibeen-reached thechamber 30fstem '29, and a-associatedparts maycontinue to settledown- -ward'ly at a 'defiriite predeterminedrate depending upon the rapidity with which the trapped fluid escapes.Mechanismds provided-so that as thing as the chamber'BO is at or--abovea predeter- -mined position -themember 14 of theboltwork.-c'annot be movedtdunlocking position, but as :=soon:'as the chamber30reaches or drop'sbelow the predetermined position, then-the boltwork isre'leased and maybeiunlocked. Hence, it folilowsithat-a'fterthe"chamber' 30 has'been charged with trapped fluid and released so thatit may tbeginitodescendthe boltwork 14 remains' locked for apredetermined time interval. Thistime interval is -the length o'ftimenecessary for a sufficient amountofithe trapped fluid to escape from*the chamber 30 so that the chamber moves downwardlym the predeterminedunlocking position. Thus this mechanism may I be: described fluidcontrolled means for keeping the bolt in locked position for apredetermined time interval.

Preferably the means for releasing the trapped fluid from the chamber isadjustable so that the rate at which the fluid escapes may be varied,and thus the time interval during which the time lock is efiective maylikewise be adjusted or varied. vIn this --,way the-@mechanism may beset .to-be. effectivejforla period of from afewmoments up to severalhours, as desired.

:The fluid releasing means in its preferred form comprises a passageway35 (Fig. 4) in the stem '-29-communicating at its lower end with theinterior of the'chamber 30; The fluid escaping 1from -theg-chamber flowsupwardly through this passageway toanvenlargement 36, and thence outthrough a. lateral vent 37. The stem 29 is hollow-fromthe enlargement 36on up to its top, .andds threaded as indicated at 38. A member 39threaded to cooperate with the threads 38 car- :riesra "needlewalve atits lower J end, :which :controlsithe flowrof fluid throughthelpassageway '35. Byl means of :a long: screw. driver insertedlinthehollow-stm29fthrough its top and engaging the usual. screw slot 1 inthe .top of the member .1539, theilatter may I'belturned to adjust itupor down andthus to adjust :theneedle'valve 40 to permit fluid tobereleased .through the-passageway-35 M any desired rate.

.Another possible embodiment of meansfor-congg 1 trolling therelease of:the fluid employs a porous plugas illustrated in Fig. 5. Here the' stem29a has a somewhat larger passageway- 35a communicating with theinterior of the-ChamberBO, and

leading-"to. an-enlargement 3fia in 'the stem, whichenlargementcommunicates with avent" 37a passing through 1 the wall of the stem. -*Ashoulder 542 is formed at the junction ofthe passageway =3'5wwiththeenlargement 36a, and a porous plug is seated-on 'this=shoulder, agasket43 preferably beinginterposed-between the plug and the shoulderso:as -to"form a perfectly air=tight joint. capeiiinw.the way in whichit-entered. Some The i porous pl'ug may comprise, for example,

*any suitable substance 44 having more or less poro'sity so that flui'dcan-=esoape therethrough,

which substanceis preferably surrounded by a sleeve 45 of metal or othersuitable material.

' Numerous porous materials --are known and may be used satisfactorily,some of such materials permitting passage of fluid therethroughrelatively rapidly; and others-permitting such pasbe either a naturallyoccurringip'orous :mineral,

' such for example as silicon, or an' artificially made productsuch forexample as porous plaster, or

any other suitable product-"or material. When it"is desired "to varythelength 'of time during whi'ch this time' lock mechanism-is effective theporous plug may be removed and replaced -by another poro'usplug of adi'fierent material, or

of a diiTerentlengthof the same "material.

\ T0 1 make the porous plug readily removable and replaceable, the stem2 9a is made'hollow all the way 'from the-shoulder'42'to'the top o'f the5 Stem, and ofa sufficient diameter sothat th'porous plug may beinserted-and removed through the top of the stem. After inserting aplug, ac'oil spring-46 may be placed on-the -topof theplug and aplug 47may then be-screwed into-the top of the stem 29a, to place the spring 46under In the 'form of the invention illustrated in Figs. 3 and 4, thetop o'f thestem' '29 is provided door 11.

' with a relatively wide laterally extending flange 50, with which theoperating means cooperates as hereafter. described. In the porous plugform of invention illustrated in Fig. 5, a similar flange 5011 may beformed either as a part of the stem ber 56, which rests loosely upon theflange 50.

When this blocking member is in an elevated position, as illustrated inFigs. 2. and 3, it lies in member 56 drops'downwardly, however, to aposition such as illustrated in Fig. 1, then it no ,longer interfereswith movement of the lug 57,

and bolt member 14 may then be moved 1eftwardly to an unlocking positionso far as this blocking member is concerned.

It will be seen that if the stem 29 be raised her 30 and the blockingmember 56'with it, so

that the blocking memberwill be substantially in the position shown inFigs. 2 and 3, and will prevent unlocking of the boltwork. Likewise thechamber 30:will be substantially in the position shown in Fig.3, so thatit. will become fllledwith Now if the stem 29 is released, the chamber30, stem 29, and locking member56 will settle downwardly, but thedownward movement will be relatively slow, depending upon and controlledby the rate of escape of the fluid trapped within the chamber 30. As thechamber, the stem,-and the blocking member descend,'the boltwork of thesafe will be prevented from being unlocked so long as the top of theblocking member 56 is above the bottom of the lug 5'7, and not until thetop of the blocking member drops below the bottom of the lug,-willithe'boltwork of the safe be released for unlocking. i

It is to -be especially noted that the blocking member 56is not rigidlyconnected tothe stem 29, but is loosely. connected thereto, preferablysimply resting on top of the stem. This is advantageousbecause if itbeattempted to move the boltwork prematurely so" as to press the lug 57against the blocking member 56, this will not strain or injure the. timelock mechanism in any way or prevent it from fiuictioning, but willsimply tend to tilt the blocking member 56 and will hold it rigidly inits guide 55, while the stem 29 will drop away from thebottom of theblocking member and continue to descend. As soon as the pressure of thelug 57 against the blocking'member56 is removed, the blocking memberwill drop downwardly in its guide until it again rests on the top of thestem 29.

' the combination lock 20. to itsuppermost position, it will carry thechamsuccessive oscillationso'f the lever.

when the blocking member j 56 rests upon the stem. Thus the .time lockmechanism cannotbe circumvented from the outside of the; safe, but onthe contrary; when a premature attempt to unlock the boltwork ismade,'the time lock mechanism will run still more slowly rather thanfaster, and the person attempting to unlock the boltwork prematurelywill have 'a still longer time toiwait' until the boltwork can beunlocked.

Various means may beemployed for initially setting or starting theoperation of the time lock mechanism. In the present instance it isfound convenient to do this by means of a lever 60 pivoted atan'intermediate point 61, and having one end 62 in position to underliethe flange 50 on the stem-29; This end 62 of the lever is made thickerand sufliciently heavier than the opposite- The opfulcrum 61, lies inthe path of movement of a pin 63 fixed to the disk 22 on the spindle 21of Whenever the spindle 21 is turned to operate'th'e combinationlock,the pin 63 will come into contact with the righthand end of the lever 60and will depress this end to the'po'sition shown in Fig. 2, so that theleft hand end 62 is raised, and through contact with the flange 50 itraises the stem 29, the fluid trapping chamber 30, and the blockingmember 56.

A part of the lever 601s curvedto conform to the arc in which the pin-63 moves,'as indicated at64, so thatduring a substantial part of themovement of this pin the 'lever willbe maintainedin its maximum elevatedposition shown in Fig.2. Thus the wear onthe lever, caused by lockedposition, with the bolt 23 withdrawn, the I pin 'isnear the top of thedisk and does not interfere with the return movement of the lever 60 tothe'normal position shown in Figs. land 3.

In operation, when the sate is locked, the parts are in the'normalposition shown in Fig. 1 with -the boltwork held from being unlocked bythe bolt 23 of the combination lock, and with the blockingmember 56depressed to unlocked position. When it is desired to unlock the safe,the combination lock is operated to withdraw the bolt '23. Eachrevolution-of the disk 22 in effecting such operation of the combinationlock oscillates the lever 60 and the first such oscillation raises stem'29; chamber 30, and the blocking member "56 "to the-position shown inFig. 2.

f During subsequent revolutions of 1 the stem 21,

the lever 60 will again be'oscillateds'o that stem 29 and chamber. 30are brought back to their initial elevated position at each "revolutionof the spindle 21,; although-some slight settling of the chamberand stemmay take place between The last revolution of thecombii ration spindle21;inopcrating the combination lock, once more elevates the chamber =30to its initial'position, andthen releases "it for its downward movement.'The final motion of the combination spindle in withdrawing thecombination bolt 23 from the position shown in Figs. 1 and-2"tothe-positionshown in'FigJ-B wilLleavethe pin :63- 'in'an "elevatedpoposition shown 'in Fig. 3.

sition out of contact :with thetlever 60, soithat this lever may drop bygravity to the position shown Eig. 3,and..will remain there, permittingthe chamber 30,, stem 29, and. blockingmember56 to descend in accordancewithzthe. escape of fluidfrom" the chamber.

At this timezthe parts are substantially in the The boltwork. of thesafe is no'longer obstructed by' the bolt-'23 of the combination look,but; it'is obstructed by the blocking member 56, sothat the safe. cannotbe opened. The blocking member moves downwardly together with the stem29 .and the chamber, in accordancewith. the release of fluid from thechamber, one intermediate position of the parts being illustrated indotted. lines inFig. .3.

.At the end of the predetermined time interval, the-length of which isdeterminedby the, rate of escape of fluid from .the chamber. 30, theparts will have settled .sufiiciently so that'the. top of theblockingmember'56 isbelowthe bottom of the lug 57, and no longerobstructs the boltwork. The handle 16 onthe exterior of the safe maythen be oscillated to move the boltwork member-14 and the bolts12jleftwardly to unlock the safe.

)Thetime lock mechanism has beenrdescribed as setin operation by thecombination look, so as to delay theopening of the safefor apredeterminedlength ,of time after the combination lock isoperated.While;the time lock mechanism is well-adapted for use inthis connectionit should be clearly understood that it is capable also ofmany otheruses, and is not limited inits application to operation by acombinationlock. The time lock mechanism mayflbe'setiinto operation, for example,by-operation of any form of lock other than a combination lock, such asan ordinary key lock, or operation ofthe timelock may beactuated by anyother suitable'means or devices not connected with. or .dependent upon alock of any kind. The time lock mechanism may also bearrangeditgdesired, to be set into operation at the timethe-safe is locked, soas to prevent it from being openeduntil apredetermined lengthof-time:has.-elapsed after it was last locked. i

As an additional safeguardto preventthe time look from beingcircumvented, means is provided for retaining the sealing liquid inthereceptacle even if the safeiis tipped on;itsside or upside down, asmight'be done in the case :of a small safe. Such sealing meanspreferably comprises a battle member 70 within the receptacle arrangedso that even if the receptacle be turnedon its sideor inverted, theliquid sealing means is kept away from the aperture 28 and cannot flowout through the aperture.

:This-bafile, member 70,-. as clearly shown in Fig. 3,;may;be;.intheform of a cup shaped member of slightlylarger'size than the chamber30,fixed securelyi-by a liquid-tight 'joint to the top of the receptacle25 in *such, position that the chamber .30 may flt inside the bafilewhen elevated to its .upper position. Theoavity within the receptacle'25 is,enlarged at ll-around'the bafile 70 to provide a-cavityofsubstantial size which will hold the sealing liquid. 'Henoe, ,if thereceptacle 25 be turned on its side, or upside down, the sealing liquidwill'run intothe=cavity 71 around the outside of the bafiie '70, andis-thus held away from theaperture 28, so that it cannot escape throughthe aperture.

Whilethe receptacleis on its side orinits upside ;d0.w.n position, thetime, lockmech nism .Will

' not operate because it "dependsmpon gravity for its operation. Assoon-.as'the receptacle is turned back to its normal.uprightposition,thesealing liquid. which has been held from escape-bythe baffle '70will run back to itsnormal position in the cavity 27,so that it:will properly seal the fluid within the chamber 30, and thetime'lock mechanism will function: in the proper manner.

Usually thespace between the .stem 29 and the sides of the aperture. 28issuificientto admitthe required quantity of gas to be trapped withinthe chamber 30. .If this space. shouldproveinsufficient for thatpurpose, however, a vent 75 may be provided for admittinggas morerapidly to the receptacle 25 when'the chamber 30 is elevated.

.A strainer comprising.porous.material '76, such as cotton or the like,may be held inplace by. a cap 77 over the vent "75, sothat any gasentering through this vent is strained and foreign matter is prevented.from entering with it. Furthermore if the receptacle is placed onitsside.or upside down temporarily, the strainer 76 will prevent thesealing liquid from running outthroughi the vent.

Preferably the closure 26 of the receptacle25 is sealed in such mannerthat itcannot be removedsurreptitiouslyfor.the purpose of extracting allor a part of the sealing liquid from the receptacle. Thismayconveniently be .accomplished byholding theclosure 26 inzplace bylughave been disclosed, it is to beunderstood that the inventive ideamay be carried out in anumber of ways; This application is therefore notto be limited to the precise detailsdescribed, but 'is'intended to coverall variations and modifications thereof falling within the spirit ofthe invention or'the scope of the appendedclaims.

I claim:

1. Locking .mechanism .for safescomprising means for controllingmovementof abolt, said means comprising a chamber enclosing a quantity offluid,anda porousmember through'which fluid may escape :from said chamber.

2. Locking mechanism for safes comprising means for controlling,movement "of .a bolt,.said means .comprising a chamber. enclosing a.quan- .tity of fluid, a passageway through whioh'the enclosed fluid maybe released, and a porous member in said passageway vfor:controlling therelease of fluid therethrough.

3. Locking mechanism for safes. comprising means for controllingmovement of a bolt, said means comprising a'chamber enclosinga quantityof fluid, a passageway through which the enclosed fluid may be released,a seatassociated with said passageway,-a porous member mounted on, saidseat for controlling the release of fluid through said passageway, andresilient means for holding said porous member in cooperative .rela-'tion to said seat.

4. Locking mechanism for safes comprising means for controlling movementof a .bolt,.said

means comprising a chamber enclosing .a quantity of fluidzand porousmeans lforycontrolling release of fluid from said chamber at apredetermined rate.

5. Locking mechanism for safes comprising means for controlling movementof a bolt, said means comprising a chamber enclosing a quantity ofrelatively light fluid, a heavier fluid for sealing the relatively lightfluid in said chamber, and means for releasing the enclosed light fluidfrom said chamber.

6. Locking mechanism for safes comprising means for controlling movementof a bolt, said means comprising an inverted cup like chamber fortrapping a relatively light fluid, a heavier fluid in which the loweredge of said chamber is immersed to seal said relatively light fluid insaid chamber, and means for releasing said relatively light fluid fromsaid chamber.

7. Locking mechanism for safes comprising means for controlling movementof a bolt, said means comprising an inverted cup like chamber fortrapping a quantity of gas, a body of liquid in which the lower edge ofsaid chamber is immersed to seal said gas in said chamber, and

means for releasing said gas relatively slowly from said chamber.

8. Locking mechanism for safes comprising means for controlling movementof a bolt, said means comprising an inverted cup like chamber fortrapping a quantity of gas, a body of liquid, means for raising thelower edge of said chamber above said liquid to admit gas to saidchamber and for immersing the lower edge of said chamber in said liquidto seal the gas in the chamber, and means for releasing the gas from thechamber.

9. Locking mechanism for safes comprising a movable member, an invertedcup like chamber for trapping a quantity of gas, a body of liquid inwhich the lower edge of said chamber is immersed to seal the trapped gastherein, means for releasing gas from said chamber so that the chambermay settle into said liquid, and a blocking member controlled by saidchamber for blocking movement of said movable member until said chamberhas settled to a predetermined position.

10. Locking mechanism comprising a bolt, a lock for preventing unlockingmovement of said bolt, an inverted cup like chamber, a body of liquidassociated with said chamber, means effective upon actuation of saidlock to trap a quantity of gas in said chamber and to immerse the loweredge of said chamber in said liquid to seal the trapped gas therein,means for releasing gas from said chamber so that the chamber may settleinto said liquid, and a blocking-member controlled by said chamber forblocking unlocking movement of said bolt until saidchamber has settledto a predetermined position.

11. Looking mechanism comprising a movable member, an inverted cup likechamber for trapping a quantity of gas, a body of liquid in which thelower edge of said chamber is immersed to seal the trapped gas therein,means for releasing gas from said chamber so that the chamber may settleinto said liquid, a stem secured to said chamber to move therewith, anda blocking member cooperating with said stem and movable therewith forblocking movement of said movable memberuntil said chamberhas settled toa predetermined position, said blocking member resting loosely on saidstem so that transverse pressure on said blocking member will notprevent movement of said stem and chamber. 12. Looking mechanismcomprising a movable member, an inverted cup like chamber for trapping aquantity of gas, a body of liquid in which the lower edge of saidchamber is immersed to seal the trapped gas therein, a stem secured tosaid chamber to move therewith, means within said stem for controllingrelease of gas from said chamber so that the chamber may settle intosaid liquid, and a blocking member associated with said stem and movabletherewith for blocking movement of said movable member until saidchamber has settled to a predetermined position.

13. Looking mechanism comprising a receptacle having an aperture in awall thereof, a body of liquid within said receptacle, an inverted cuplike chamber within said receptacle, said chamber being arranged to havethe lower edge thereof immersed in said liquid to trap a quantity ofgas, a stem attached to said chamber and passing loosely through saidaperture, and means for preventing escape of said liquid through saidaperture'when said'receptacle is inverted.-

14. Looking mechanism comprising a recepand a bafile wall for holdingsaid liquid away from said aperture when said receptacle is inverted sothat said liquid cannot escape through said aperture.

15. Locking mechanism comprising a receptacle, means within saidreceptacle for trapping a quantity of gas, a vent for admitting gas tosaid receptacle, gasstraining means associated with said vent, a bolt,and mechanism cooperating with said gas trapping means for holding saidbolt against movement.

16. Locking mechanism comprising a bolt, a combination lock forpreventing unlocking movement of said bolt, an inverted cup like chamberfor trapping a quantity of gas, a body of liquid for sealing the trappedgas in said chamber,

means for releasing gas from said chamber so that the chamber may settleinto said liquid, mechanism controlled by said chamber for preventingunlocking movement of said bolt until said chamber has settled to apredetermined position, and means effective upon actuation of saidcombination lock to raise said chamber until the lower edge thereof isabove said body of "liquid in order to admit gas to said chamber and torelease said chamber so that it may settle into said liquid inaccordance with the release of gas from the chamber.

GERRIT D. HILL.

